Electronic organ employing automatic coupling of solo and accompaniment notes

ABSTRACT

An array of tone signal sources is controlled by solo keys and by accompaniment keys for transfer respectively to solo tonecolor filters and accompaniment filters, and thence to a loud speaker, in the manner usual in electronic organs. Tones collected in response to actuation of accompaniment keys are also applied to the input of a normally inhibited gate having its output connected to solo filters. Actuation of any one or more of the solo keys uninhibits the gate, selectively either transiently or for the duration of the actuation, by generating appropriate gate control pulses. A second normally inhibited gate is paralleled to the first gate, and similarly controlled, but its input circuit is a further gate which is supplied with reiteration voltage.

United States atent 13,565,995

[72] Inventor David A. Bunger 3,040,612 5/1962 Dorf 84/1 1 7 Cincinnati,Ohio 3,109,341 11/1963 Gibbs 84/1.01X [21] Appl. No. 768,321 3,223,76812/1965 Munch et al..... 84/1.01 [22] Filed Oct. 17,1968 3,461,2178/1969 Omura et a1. 84/1.08 [45] Patented Feb. 23, 1971 Prima [73]Asslgnee gis i rgg g g Assistant Examiner-Stanley J. WitkowskiAttorneysW. ll. Breunig, D. H. Baldwin Co. and Hurvitz,

Rose & Greene [54] ELECTRONIC ORGAN EMPLOYING AUTOMATIC COUPLING OF SOLOAND ACCOMPANIMENT NOTES ABSTRACT: An array of tone signal sources iscontrolled by 21 Claims 2 Drawing Figs solo keys and by accompanimentkeys for transfer respectively to solo tone-color filters andaccompaniment filters, and U-S- then e t a l ud eaker in the mannerusual in electronic or. f Cl i Gloh 1/00 gans. Tones collected inresponse to actuation of accompaniment keys are also to the input of anormally 1-08; 84/1-01, 11911150) gate having its output connected tosolo filters. Actuation of 56] References Cited any one or more of thesolo keys uninhibits the gate, selectively either transiently or for theduration of the actuation, by

UNITED STATES PATENTS generating appropriate gate control pulses.3,247,310 4/1966 Stinson 84/ 1.17 A second normally inhibited gate isparalleled to the first 3,283,056 11/1966 Cookerly et a1. 84/ 1.01 gate,and similarly controlled, but its input circuit is a further 2,988,9455/1961 Osborne et a1 84/1.01 gate which is supplied with reiterationvoltage.

PATENTEU FEB23 l97| C 68:? INVENTOR DAVID auueen s'r an SIN .5320 gas;@985 58.5 A

m ii.

In -LIJ ATTORNEY 5 the solo note.

between circuit and gate 32.

BACKGROUND or Tl-lE INVENTION Conventional coupler systems forelectronic organs cause signals keyed from one keyboard, for example, topass through the tone-color circuits of another keyboard, whether or notnotes are played on the other keyboard. U.S. Pat. Nos. 3,247,3l toStinson and 3,283,056 to Cookerly et al., by means of elaborate andexpensive keying systems, teach causing notes played on an accompanimentmanual to be heard through solo filters only when a solo note is played,but in the octave immediately below the solonote. The present inventionremoves the recited limitation and simplifies the patented systems.

The present invention provides a relatively simple system for causingnotes played on an accompaniment keyboard to be heard through solofilters at the same,or harmonically related, pitches as the notes playedon the accompaniment manual, only when a solo note is played,but'regardless of the pitch of SUMMARY OF THE INVENTION A trigger pulse,derived from a direct current circuit keyed concurrently with a signalkey switch is in a solo keyboard is shaped and used to turn on a PETgate between an accompaniment key switch and a solo tone-color circuit,so that BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a block diagram of apreferred embodiment of the invention.

FIG. 2 is a circuit diagram of the system of FIG. 1.

DESCRIPTION OF THE PREFERREIIl EMBODIMENT In FIG. 1, sources 1 and 3 ofmusical signals f, and respectively, are shown connected via keyswitches 5 and 7, respectively, activated by keys (not shown) indifi'erent keyboards, tone-color filters TC, and TC,,, respectively, andstop switches 9 and 11, respectively, to arr-output system composed ofan amplifier 13 and loudspeaker 15. Source 1 has also a path to theoutput system via a percussion gate 17, tone-color filter PERC and stopswitch 19. In addition, a source of direct current voltage v.-isconnected via a trigger and pulse-shaping circuit 21 and a normallyinhibited gate 23 to the input side of tone-color filter TC,. There isalso a path from nigger and pulse-shaping circuit 21 via an auxiliarykey switch 25 (ganged to switch 5) to gate 17. The output side of switch7 is also connected to gate 23, as shown. A switch 27 is In operation,closure of key switch Sdirects a signal from tone source 1 directly viafilter TC,, for coloring thereby, and via switch 9 (if closed) to theamplifier 13 and loudspeaker 15 for conversion to. sound. Concurrently,switch 25 is closed and direct current voltage v. uninhibits gate 17. Iftab switch 19 is closed, signal will pass from source 1 through gate 17for coloring by tone-color filter PERC and conversion to sound in theloudspeaker 15. If switch 7 (in anotherkeyboard or in the accompanimentsection of a split keyboard) is closed, signal at frequency f, will passfor coloring byjTC, and for conversion to sound in loudspeaker 15, iftab switch 11 is closed. However, closure of switch 25 generates a pulsein circuit 21, which is there shaped, and it switch 27 is closeduninhibits gate 23, whereupon signal can also pass from source 3 viagate 23 to tone-color filter TC,, for conversion to sound, if switch 9is closed. Thus are illustrated in FIG; lithe basic essential elementsof an automatic coupling system wherein a keyed signal in one keyboardwill be heard through a filter in another keyboard, only if and when anote is played on the other keyboard.

Sources 2, 4, 6 and 8 of FIG. 2 represent four of a gamut preferably offrequency-dividing flip-flop tone sources, as known in the art, and theygenerate tone signals corresponding to notes C B C and 15,,respectively, of the equally-tempered scale. Source 8 is connected viakey switch 10, operable concurrently with key switches 12 and l4 by akey 16 of a solo keyboard 18, represented by dashed lines. Switches 10and 12 are preferably of the variable-resistance type disclosed in U.S.Pat. No. 3,206,701 to Gregory, the latter switch being connected to asource E of tone signal. Switches 10 and 12 are respectively connectedto a suitable tone-color filters 8'TC and 4'TC, which, in turn areconnectable by stop-tab switches 20 and 22, respectively, to a collector24, thence to a suitable amplifier 26 and loudspeaker system 28. Theswitch 14 may be of a direct-contact type and is shown connected betweena percussion gate 30 and a terminal 32 from a negative source (notshown) of direct current via two series resistors 34 and 36. Thepercussion gate 30 may be of a suitable type known in the art, providinga sharp rise and gradual decay of tone signal passing therethrough fromthe source 8 to a suitable filter PERC in response to application of DCgating voltage. The filter PERC may be connected to the amplifier 26 andloudspeaker 28 via a tab switch 38, Branches 40, 42 and 44 indicate thatsignals from other key switches actuated from keyboard 18 may beconnected to the tone-color filters according to usual practice.

Connected to the junction 128 of resistances 34 and 36 is one tenninalof capacitor 48, the remaining terminal being connected directly to thebase of transistor T,. The emitter of T, is connected directly toterminal 32, and a resistance 50 is connected from base to emitter ofT,. The emitter of T, is also connected to ground via series resistances58 and 60, and its collector is connected to ground via seriesresistances 54, 56. The collector is thus positive with respect to theemitter which is maintained at 100 v. below ground.

T, is normally nonconductive, but on closure of switch 14, current isdrawn .in at the gating terminal :of percussive gate 30, and a voltageis developed across resistor 36, which is transferred as a transientpulse to the base of T,, and renders the latter conductive transiently.If switch 52 is closed, however, the capacitor 48 is short circuited anda steady state conductivity for the duration of closure of switch 14 iseffected.

The junction of collector load resistances 54, 56 is directly connectedto the base of NPN transistor T,, the emitter of which is connected backto ground in the junction of resistances 58, 60. The collector of T, isconnected to ground via load resistance 66. T, is therefore normallyconductive so long as T, is nonconductive.

The voltage at the emitter of T, is -12. The emitter of T, is connectedvia a large resistance 64. to a stationary switch contact 61 of a switch62. The collectorof T, is connected via series resistances 68, 70,to asecond stationary switch contact 61a. The resistances 68, 70, areshuntedby a diode 72 having its anode connected to the collector of T,,and which is therefore nonconductive of transistor current. Between themovable contact of switch 62 and ground is connected a capacitor 71, andthe movable contact is also connected to the gate terminal G of a fieldefiect transistor (FET) T whose drain terminal D is connected via acoupling capacitor 74 to filter 4'TC. A shunt resistor 76 is connectedbetween terminal D of FET T and a common return path ground. The sourceterminal S of T, has one path via a-resistor 78 to ground and anothervia coupling capacitor 80 and series resistor 82 to path 84. Thelast-mentioned group of components comprise a gate 73, the operation ofwhich will be discussed hereinafter.

The path 84 serves to connect tone source 8 via variable-resistance keyswitch 86 (operable by key'88 of an accompaniment keyboard 90) to anaccompaniment tone-color filter 4'TCA. Tab switch 92 connects, at will,this filter with amplifi 94, actuated concurrently with switch 86,connects tone source 4 to a second accompaniment filter 8'TCA, with tabswitch 96 connecting, at will, thisfilterto amplifier 26 and loudspeaker28. A second key 98 of the keyboard 90 may ac tuate variable-resistancekey switches 100 and 102 to connect tone sources 6 and 2, respectively,via collectors 104 and 106, respectively to filters 4'TCA and 8'TCA,respectively.

An alternate path fromcollector 106 to the output system (amplifier 26and loudspeaker 28) exists via a resistor 108, a coupling capacitor 110,a PET T,, a second gate 112 (which may be similar to gate 73) and afilter 8'TC. The FET T and its associated normal components, including ashunt resistor 114 connected from source to ground, comprises areiteration gate, the gate terminal G of T, being connected to areiteration oscillator 116 via a switch 117 and a filter network 118.The network 118 is composed of resistors and capacitors, as shown, andserves to filter high frequencies from the oscillator output. Theoscillator 116 comprises a-rnultivibrator of substantially conventionalcharacter, diodes 120 and 122 and capacitor 124 sewing not only toassure the starting of oscillations but also to delay them slightly. Apotentiometer 126 provides control of the reiteration rate of theoscillator.

In operation, assuming that a chord composed of notes C and E is held onthe accompaniment keyboard by depressing 1 keys 88 and 98, tone signalspass from sources 2, 4, 6 and 8 through key switches 102, 100, 94 and.86, respectively, via collectors 104 and 106 to the output system viaeither filter 4'TCA or 8TCA or both depending on which of switches 92and 96 is closed. Obviously, if switches 92 and 96 are open, no signalswill be heard in the output system. However, if a note E, (which, ofcourse, would hannonize with C, and E were played on the solo manual bydepressing key 16, it would be heard in the output system if tab switch20 were also closed,

the signal passing via switch 10 as filtered by 8'TC. B, would also beheard, via key switch 12, if tab switch 22 were closed, as colored byT'TC. However, the concurrent closing of switch 14 causes direct currentto. pass from terminal 32 through resistors 36 and 34, thru raising thepotential of junction 128. Assuming first that switch 52 is closed (forcontinuous operation of the trigger and pulse-shaping circuit 46) andswitch 62 is in the upper position, the DC level of the base oftransistor T,, which is normally nonconductive, is raised with respectto the emitter and T, conducts. Conduction in T, causes the base of Twhich is normally conductive to go negative,'thus cutting T, off. Thencapacitor 71, the upper plate of which has been charged negatively,discharges quickly via diode 72 and resistor 66, thus raising thepotential of the gate terminal 6 of FET T causing it to conduct signalfrom the line 84 through resistor 82, capacitor 80, capacitor 74, to4TC, thence to the output system if tab switch 22 is closed. Thesignalwill be heard so long as the key 16 is held. Upon release of the key,'1, turns off, and '1, turns on again at a rate determined by the timeconstant of the'ca'pacitor 71 and the resistors 70 and 68, as capacitor71 charges to a negative voltage. FET T, again becomes nonconductive,turning off the signal from source 8 via key switch 86. I v v If theswitch 52 is in the pizzicato (PlZZ) position, the operation starts inthe same way, but transistor T, quickly turns off as capacitor 48charges up, and then discharges. By the tiine it discharges, viaresistors 36 and 50, T, has become nonconductive again, and the circuit"I, wait for another closing of key 16 before being operative again. Ifthe selector switch 62 is in the lower position, the gate G of PET T,remains at -l2 v. keeping capacitor 7l charged, and '1; does not respondto operation of key 16 (or any other key in the solo manual).

Gate 112 is similar to that of gate 73 However, the reiteration gateincluding T being in series with gate 112, a signal Thus, accompanimentchords cannot only be coupled to a solo manual, automatically playableonly when solo notes are played, but the pitch of the chords, as relatedto the solo notes, may be selected as desired by the operation oftone-color tab switches, such as 20 and 22. 3

While I have described and illustrated one specific embodiment of myinvention, it will be clear that variations of the details ofconstruction which are specifically illustrated and described may beresorted to without departing from the true spirit and scope of theinvention as defined in the appended claims.

lclaim: v

1. In an electronic organ having a gamut of tone signal sources, a firstkeyboard, a second keyboard, a first tone-color filter, a secondtone-color filter, an output system, a first key switch operable by akey in said first keyboard and coupled between one of said sources andsaid output system via said first tone-color filter, a second key switchoperable by a key in said second keyboard and coupled between another ofsaid sources and said output system via said second tone-color filterthe combination comprising:

a direct current supply;

an auxiliary key switch ganged to said first key switch;

a trigger and pulse-shaping circuit means coupled between said auxiliarykey switch and said direct current supply and responsive to closure ofsaid auxiliary key switch for generating a control pulse; and

a normally-inhibited gate coupled to said trigger and pulseshapingcircuit, and responsive to said control pulse to uninhibit said gate,said gate being also coupled between said second key switch and to saidfirst tone-color filter, whereby actuation of said key in said firstkeyboard closes said auxiliary key switch creates a pulse in saidtrigger and pulse-shaping circuit operative to uninhibit said gate so asto cause a signal to flow between said other source and said outputsystem via said second key switch and said first tone-color filter whensaid key in said second keyboard is actuated.

2. The combination according to claim 1, including:

a third tone-color filter;

a third key switch operable by said key in said first keyboard andcoupled between a further one of said sources and said output system viasaid third tone-color filter;

a fourth tone-color filter;

a fourth key switch operable by said key in said second keyboard andcoupled between one of said sources and said output system via saidfourth tone-color filter; and

I a second normally-inhibited gate coupled to said trigger andpulse-shaping circuit, and responsive to said control pulse to uninhibitsaid gate, said second gate being coupled between said fourth key switchand said third tone-color filter, whereby actuation of said key in saidfirst keyboard closes said auxiliary key switch,-thereby creating apulse in said trigger and pulse-shaping circuit operative to uninhibitsaid second gate and to cause a signal to flow between said one of saidsourcesand said output system via said fourth key switch and said thirdtone-color filter,

when said key in said second keyboard is actuated.

3. The combination according to claim 1, including a reiteration gatecoupled between said second key switch and said secondnormally-inhibited gate; 1

a reiteration oscillator coupled to said reiteration gate for renderingsaid reiteration gate reiteratively inhibited and uninhibited; and

switch means coupled between said reiteration gate and said reiterationoscillator.

4. The combination according to claim 3 wherein said reiterationoscillator includes means for at altering the rate of oscillationthereof.

may be periodically interrupted (with switch 117 closed) by 5. Themethod of automatically coupling a signal derived the on-off operationof T, as controlled by the reiteration oscillator 116. The reiterationis effective as illustrated, only on an 8'voice in the solo manual.Should reiteration be desired for a 4'voice, a reiteration gate could beinserted between gate 73 and line 84.

from closing a key switch in one keyboard to a tone-color filter foranother keyboard which comprises:

deriving a pulse from depression of any key in said other keyboard; Yamplifying and shaping said pulse; and

applying said pulse to uninhibit a normally inhibited gate operativebetween said key switch in said one keyboard and said tone-color filter.6. In an electronic organ; a series of tone signal sources; an array ofsolo keys; an array of accompaniment keys; a solo tone color filter; anaccompaniment tone-color filter; a loudspeaker system connected incascade with said tonecolor filters; means responsive to actuation ofselected ones of said solo keys for connecting corresponding ones ofsaid tone signal sources to said solo tone-color filters; meansresponsive to actuation of selected ones of said accompaniment keys forconnecting corresponding ones of said tone signal sources to saidaccompaniment tonecolor filter; and gate means responsive to actuationof any one or more of said solo keys for connecting tone signal sourcescalled for only by the actuated accompaniment keys to said solotone-color filter. 7. The combination according to claim 6, wherein saidgate means is arranged and adapted to be operative while said any ofsaid solo keys are actuated for the duration of the actuation. 8. Thecombination according to claim 6, wherein said gate means is arrangedand adapted to be only transiently operative in response only to initialactuation of. any said solo keys regardless of the then actuatedcondition of other of said solo keys.

9. In an electronic organ: a series of tone signal sources; a array ofsolo keys; an array of accompaniment keys; a solo tone-color filter; anaccompaniment tone-color filter; a loudspeaker system connected incascade with said tonecolor filters; means responsive to actuation ofselected ones of said solo keys for connecting corresponding ones ofsaid tone signal sources to said solo tone-color filter; meansresponsive to actuation of selected ones of said accompaniment keys forconnecting corresponding ones of said tone signal sources to. saidaccompaniment tonecolor filters; means responsive to actuation of anyone or more of said solo keys for connecting tone signal sourcescorresponding only with the actuated accompaniment keys to said solotone-color filter, wherein is provided a selective twocondition switch;and means comprising a pulse shaping circuit responsive according to thecondition of said selective two-condition switch for connecting tonesignal corresponding with accompaniment keys to said solo tone-colorfilter transiently on actuation of any of said solo keys or for theduration of actuation of said solo keys. 10. The combination accordingto claim 9, wherein said last means includes a normally nonconductivetransistor and a normally conductive transistor connected in cascade:

means responsive to rendering said normally nonconductive transistorconductive to render said normally conductive transistor nonconductive;a gate connected between said tone sources and said solo tonecolorfilter; I a means uninhibiting said gate in response to the conductivecondition of said normally conductive transistor and inhibiting saidgate in response to the nonconductive condition of said normallyconductive transistor; and means applying to said pulse to renderconductive said normally nonconductive transistor selectively on atransient and a steady state basis. 11. In an electronic organ: a sourceof negative voltage; a resistance connected in series with said sourceof voltage;

a plurality of load circuits selectively connected in cascade with saidresistance;

a plurality of key switches;

means responsive to closure of any one or more of said key switches forcompleting a circuit from said source of voltage through said resistanceto one or more of said load circuits to develop a control pulse;

a first transistor having a base, an emitter and a collector;

means connected said base to the load side of said resistance and saidemitter directly to said source of voltage;

an emitter resistance connected between said emitter and a referencepoint;

a collector resistance connected between said collector and saidreference point;

a gate inhibited by negative voltage applied to a gating electrode; and

means controlling said gate at said gating electrode selectivelydirectly from said emitter or in response to voltage developed across atleast part of said collector resistance.

12. The combination according to claim 11, wherein said gate includes:

a capacitor connected between said gating electrode and a referencepoint;

a terminal;

means for at will selectively connecting said capacitor to said emitterand to said terminal; and

means for discharging said capacitor in response to said control pulsedeveloped across said resistance when said capacitor is connected tosaid terminal.

13. A gating circuit comprising:

a NPN transistor having a base, an emitter and a collector;

a source of negative voltage connected to said emitter;

a load resistance connected between said collector and ground; a

a load capacitor having a first electrode connected to ground and havinga second electrode;

a timing resistance connected in series between said second electrodeand said collector;

a diode connected across said timing resistance poled in dischargerelation to said capacitor through said transistor;

means connected to said base for maintaining said transistor normallyconductive;

mean means for randomly rendering said transistor nonconductive;

a gate having a control terminal, a signal input terminal and a signaloutput terminal;

means connecting said control terminal to said second electrode;

a source of tone signal connected to said input terminal; and

a load connected to an output circuit, said gate being of the typeinhibited by negative voltage.

14. In an electronic organ:

a tone generator including a gamut of tone signal sources;

a first tone-color filter; 1

a second tone-color filter;

a loudspeaker system connected to said tone-color filters;

a first array of keys for calling forth tones in response to said tonesignal sources via said first tone-color filters; and

means responsive to actuation of any of a said first array of keys forcalling forth tones from said tone signal sources at pitches selected bykeys of said second array of keys.

15. The combination according to claim 14, wherein said last meansincludes;

means for generating a control pulse in response to each actuation ofany one or more of said first array of keys;

a collector for all tone signals called for by actuation of said secondarray of keys;

a normally inhibited gate connecting said collector with said firsttone-color filter; and

means responsive to said control pulse for uninhibiting said gate.

16. The combination according to claim 15, wherein said means foruninhibiting includes means for periodically uninhibiting at areiteration rate.

17. In an electronic organ;

a source of an array of tone signals arranged according to the equallytempered scale;

a tone-color filter;

a first normally inhibited gate;

a second normally inhibited gate;

means connecting said gates in cascade with each other between saidsource of tone signal source and said tonecolor filter;

a source of reiteration voltage;

means rendering one of said gates reiteratively uninhibited in responseto said reiteration voltage;

a' source of key controlled randomly occurring control pulses; and

means for uninhibiting the other of said gates in response to saidcontrol pulses.

18. The combination according to claim 17, wherein is included:

an array of solo keys;

an array of accompaniment keys;

means responsive to actuation of said accompaniment keys for connectingsaid tone signal sources in cascade with said gate according to the keysactuated; and

means responsive to actuation of any one or more of said solo keys forgenerating said control pulses. 19. In a music system: a keyboardinstrument having arrays of keys calling forth notes of the musicalscale, when said keys are actuated; means responsive to actuation ofcertain of said keys for providing control voltage during actuationthereof;

means for calling forth electrical tone signal from said instrumcnt inresponse to actuation only of others of said keys; and

means for converting said electrical tone signals to acoustic signalsonly in response to said control voltage.

20. The combination according to claim 19, wherein is further providedmeans for reiterating said acoustic signals.

21. An electronic musical instrument having a gamut of solo keys and agamut of accompaniment keys:

means responsive to actuation of selected ones of said accompanimentkeys for sounding corresponding accompaniment tones; and

means responsive to continuous and uninterrupted'actuation of selectedones of said accompaniment keys only with concurrent actuation ofselected ones of said solo keys for sounding said accompaniment tones inresponse to each actuation of any one of said solo tones during saiduninterrupted actuation of said selected ones of said accompanimentkeys.

1. In an electronic organ having a gamut of tone signal sources, a firstkeyboard, a second keyboard, a first tone-color filter, a secondtone-color filter, an output system, a first key switch operable by akey in said first keyboard and coupled between one of said sources andsaid output system via said first tone-color filter, a second key switchoperable by a key in said second keyboard and coupled between another ofsaid sources and said output system via said second tone-color filterthe combination comprising: a direct current supply; an auxiliary keyswitch ganged to said first key switch; a trigger and pulse-shapingcircuit means coupled between said auxiliary key switch and said directcurrent supply and responsive to closure of said auxiliary key switchfor generating a control pulse; and a normally-inhibited gate coupled tosaid trigger and pulseshaping circuit, and responsive to said controlpulse to uninhibit said gatE, said gate being also coupled between saidsecond key switch and to said first tone-color filter, whereby actuationof said key in said first keyboard closes said auxiliary key switchcreates a pulse in said trigger and pulseshaping circuit operative touninhibit said gate so as to cause a signal to flow between said othersource and said output system via said second key switch and said firsttone-color filter when said key in said second keyboard is actuated. 2.The combination according to claim 1, including: a third tone-colorfilter; a third key switch operable by said key in said first keyboardand coupled between a further one of said sources and said output systemvia said third tone-color filter; a fourth tone-color filter; a fourthkey switch operable by said key in said second keyboard and coupledbetween one of said sources and said output system via said fourthtone-color filter; and a second normally-inhibited gate coupled to saidtrigger and pulse-shaping circuit, and responsive to said control pulseto uninhibit said gate, said second gate being coupled between saidfourth key switch and said third tone-color filter, whereby actuation ofsaid key in said first keyboard closes said auxiliary key switch,thereby creating a pulse in said trigger and pulse-shaping circuitoperative to uninhibit said second gate and to cause a signal to flowbetween said one of said sources and said output system via said fourthkey switch and said third tone-color filter, when said key in saidsecond keyboard is actuated.
 3. The combination according to claim 1,including a reiteration gate coupled between said second key switch andsaid second normally-inhibited gate; a reiteration oscillator coupled tosaid reiteration gate for rendering said reiteration gate reiterativelyinhibited and uninhibited; and switch means coupled between saidreiteration gate and said reiteration oscillator.
 4. The combinationaccording to claim 3 wherein said reiteration oscillator includes meansfor at altering the rate of oscillation thereof.
 5. The method ofautomatically coupling a signal derived from closing a key switch in onekeyboard to a tone-color filter for another keyboard which comprises:deriving a pulse from depression of any key in said other keyboard;amplifying and shaping said pulse; and applying said pulse to uninhibita normally inhibited gate operative between said key switch in said onekeyboard and said tone-color filter.
 6. In an electronic organ; a seriesof tone signal sources; an array of solo keys; an array of accompanimentkeys; a solo tone color filter; an accompaniment tone-color filter; aloudspeaker system connected in cascade with said tone-color filters;means responsive to actuation of selected ones of said solo keys forconnecting corresponding ones of said tone signal sources to said solotone-color filters; means responsive to actuation of selected ones ofsaid accompaniment keys for connecting corresponding ones of said tonesignal sources to said accompaniment tone-color filter; and gate meansresponsive to actuation of any one or more of said solo keys forconnecting tone signal sources called for only by the actuatedaccompaniment keys to said solo tone-color filter.
 7. The combinationaccording to claim 6, wherein said gate means is arranged and adapted tobe operative while said any of said solo keys are actuated for theduration of the actuation.
 8. The combination according to claim 6,wherein said gate means is arranged and adapted to be only transientlyoperative in response only to initial actuation of any said solo keysregardless of the then actuated condition of other of said solo keys. 9.In an electronic organ: a series of tone signal sources; a array of solokeys; an array of accompaniment keys; a solo tone-color filter; anaccompaniment tone-color filter; a loudspeaker system conNected incascade with said tone-color filters; means responsive to actuation ofselected ones of said solo keys for connecting corresponding ones ofsaid tone signal sources to said solo tone-color filter; meansresponsive to actuation of selected ones of said accompaniment keys forconnecting corresponding ones of said tone signal sources to saidaccompaniment tone-color filters; means responsive to actuation of anyone or more of said solo keys for connecting tone signal sourcescorresponding only with the actuated accompaniment keys to said solotone-color filter, wherein is provided a selective two-condition switch;and means comprising a pulse shaping circuit responsive according to thecondition of said selective two-condition switch for connecting tonesignal corresponding with accompaniment keys to said solo tone-colorfilter transiently on actuation of any of said solo keys or for theduration of actuation of said solo keys.
 10. The combination accordingto claim 9, wherein said last means includes a normally nonconductivetransistor and a normally conductive transistor connected in cascade:means responsive to rendering said normally nonconductive transistorconductive to render said normally conductive transistor nonconductive;a gate connected between said tone sources and said solo tone-colorfilter; means uninhibiting said gate in response to the conductivecondition of said normally conductive transistor and inhibiting saidgate in response to the nonconductive condition of said normallyconductive transistor; and means applying to said pulse to renderconductive said normally nonconductive transistor selectively on atransient and a steady state basis.
 11. In an electronic organ: a sourceof negative voltage; a resistance connected in series with said sourceof voltage; a plurality of load circuits selectively connected incascade with said resistance; a plurality of key switches; meansresponsive to closure of any one or more of said key switches forcompleting a circuit from said source of voltage through said resistanceto one or more of said load circuits to develop a control pulse; a firsttransistor having a base, an emitter and a collector; means connectedsaid base to the load side of said resistance and said emitter directlyto said source of voltage; an emitter resistance connected between saidemitter and a reference point; a collector resistance connected betweensaid collector and said reference point; a gate inhibited by negativevoltage applied to a gating electrode; and means controlling said gateat said gating electrode selectively directly from said emitter or inresponse to voltage developed across at least part of said collectorresistance.
 12. The combination according to claim 11, wherein said gateincludes: a capacitor connected between said gating electrode and areference point; a terminal; means for at will selectively connectingsaid capacitor to said emitter and to said terminal; and means fordischarging said capacitor in response to said control pulse developedacross said resistance when said capacitor is connected to saidterminal.
 13. A gating circuit comprising: a NPN transistor having abase, an emitter and a collector; a source of negative voltage connectedto said emitter; a load resistance connected between said collector andground; a load capacitor having a first electrode connected to groundand having a second electrode; a timing resistance connected in seriesbetween said second electrode and said collector; a diode connectedacross said timing resistance poled in discharge relation to saidcapacitor through said transistor; means connected to said base formaintaining said transistor normally conductive; mean means for randomlyrendering said transistor nonconductive; a gate having a controlterminal, a signal input terminal and a signaL output terminal; meansconnecting said control terminal to said second electrode; a source oftone signal connected to said input terminal; and a load connected to anoutput circuit, said gate being of the type inhibited by negativevoltage.
 14. In an electronic organ: a tone generator including a gamutof tone signal sources; a first tone-color filter; a second tone-colorfilter; a loudspeaker system connected to said tone-color filters; afirst array of keys for calling forth tones in response to said tonesignal sources via said first tone-color filters; and means responsiveto actuation of any of a said first array of keys for calling forthtones from said tone signal sources at pitches selected by keys of saidsecond array of keys.
 15. The combination according to claim 14, whereinsaid last means includes; means for generating a control pulse inresponse to each actuation of any one or more of said first array ofkeys; a collector for all tone signals called for by actuation of saidsecond array of keys; a normally inhibited gate connecting saidcollector with said first tone-color filter; and means responsive tosaid control pulse for uninhibiting said gate.
 16. The combinationaccording to claim 15, wherein said means for uninhibiting includesmeans for periodically uninhibiting at a reiteration rate.
 17. In anelectronic organ; a source of an array of tone signals arrangedaccording to the equally tempered scale; a tone-color filter; a firstnormally inhibited gate; a second normally inhibited gate; meansconnecting said gates in cascade with each other between said source oftone signal source and said tone-color filter; a source of reiterationvoltage; means rendering one of said gates reiteratively uninhibited inresponse to said reiteration voltage; a source of key controlledrandomly occurring control pulses; and means for uninhibiting the otherof said gates in response to said control pulses.
 18. The combinationaccording to claim 17, wherein is included: an array of solo keys; anarray of accompaniment keys; means responsive to actuation of saidaccompaniment keys for connecting said tone signal sources in cascadewith said gate according to the keys actuated; and means responsive toactuation of any one or more of said solo keys for generating saidcontrol pulses.
 19. In a music system: a keyboard instrument havingarrays of keys calling forth notes of the musical scale, when said keysare actuated; means responsive to actuation of certain of said keys forproviding control voltage during actuation thereof; means for callingforth electrical tone signal from said instrument in response toactuation only of others of said keys; and means for converting saidelectrical tone signals to acoustic signals only in response to saidcontrol voltage.
 20. The combination according to claim 19, wherein isfurther provided means for reiterating said acoustic signals.
 21. Anelectronic musical instrument having a gamut of solo keys and a gamut ofaccompaniment keys: means responsive to actuation of selected ones ofsaid accompaniment keys for sounding corresponding accompaniment tones;and means responsive to continuous and uninterrupted actuation ofselected ones of said accompaniment keys only with concurrent actuationof selected ones of said solo keys for sounding said accompaniment tonesin response to each actuation of any one of said solo tones during saiduninterrupted actuation of said selected ones of said accompanimentkeys.